/* zround.c: round R to the nearest whole number. This is supposed to
implement the predefined Pascal round function. Public domain. */
#include <w2c/config.h>
#include "lib.h"
integer
zround (double r)
{
integer i;
/* R can be outside the range of an integer if glue is stretching or
shrinking a lot. We can't do any better than returning the largest
or smallest integer possible in that case. It doesn't seem to make
any practical difference. Here is a sample input file which
demonstrates the problem, from
[email protected]:
\documentstyle{article}
\begin{document}
\begin{flushleft}
$\hbox{} $\hfill
\filbreak
\eject
[email protected] points out we should testing against
TeX's largest or smallest integer (32 bits), not the machine's. So
we might as well use a floating-point constant, and avoid potential
compiler bugs (also noted by djb, on BSDI). */
if (r > 2147483647.0)
i = 2147483647;
/* should be ...8, but atof bugs are too common */
else if (r < -2147483647.0)
i = -2147483647;
/* Admittedly some compilers don't follow the ANSI rules of casting
meaning truncating toward zero; but it doesn't matter enough to do
anything more complicated here. */
else if (r >= 0.0)
i = (integer)(r + 0.5);
else
i = (integer)(r - 0.5);
return i;
}
